Functionalization of textile materials with silver nanoparticles

Nanoparticles gained much scientific attention in the past decade due to their specific surface chemistry and properties which are significantly different from that of the corresponding bulk materials. Silver nanoparticles were the most extensively studied and they can be already found in a wide range of commercially available products. This article reviews the latest developments in finishing of textile materials with differently synthesized silver nanoparticles. Although antimicrobial activity of functionalized textile materials was primarily discussed, the possibilities to apply silver nanoparticles as a colorant or antistatic agent were also evaluated. In addition, the effect of chemical and physico-chemical activation of fibers before loading of silver nanoparticles on their binding efficiency was considered. Taking into account the importance of environmental impact of novel technologies, potential environmental risks emerging from silver release during washing of textile materials have been also discussed.     

Properties of titanium dioxide films prepared by reactive electron-beam evaporation from various starting materials

There is a wide choice of starting materials for the production of titanium dioxide films by reactive electron-beam evaporation. We have investigated the specific merits of these materials in terms of refractive index, stress, and abrasion resistance of the resultant titanium dioxide films. The suboxides TiO, Ti2O3, and Ti3O5 as well as titanium dioxide and titanium metal were reactively evaporated, and titanium dioxide films free of absorption were obtained on substrates at 25 and 250 degrees C. On unheated substrates the refractive index, which varies from 2.06 to 2.22, the stress, and the abrasion resistance all depend on the starting material used. On substrates heated to 250 degrees C the refractive indices of all films lie closely about 2.4, and all films show high tensile stress and good abrasion resistance.     

表面包覆CeO2制备高耐候性钛白的研究

在金红石TiO2水性分散体浆料中,保持温度为70℃,PH值为9.5,分别加入TiO2基料的1%、0.2%、0.05%的硝酸铈溶液(w,以CeO2计)进行CeO2包膜,获得了光催化活性分别为0、0.13、0.47的高耐候性TiO2颜料.ξ电位测定表明,TiO2单分散的最佳条件是pH=9.5～10.5.热力学分析表明,CeO2在TiO2颗粒表面形核时的自由能ΔGh较小,CeO2可以顺利包覆于TiO2颗粒表面.     

纳米TiO2光催化功能建筑材料研究进展

以纳米TiO2为代表的纳米半导体光催化材料是目前各国科学家研究的热点.将纳米TiO2与涂料、玻璃、水泥和陶瓷等建材结合使建筑材料具有光催化功能,实现了其对表面污染物的处理及自清洁,具有很大的研究和应用价值.介绍了纳米TiO2光催化涂料、自清洁玻璃、光催化水泥混凝土和光催化功能陶瓷等的研究进展,对目前面临的问题提出了相关...     

静电组装法制备介孔TiO_2

以TiCl4和(NH4)6Mo7O24·4H2O为原料,先通过水解、静电自组装和焙烧得到TiO2/MoO3,再用NaOH溶液溶解得到介孔TiO2。用X射线粉末衍射(XRD)、透射电镜(TEM)、X射线能量色散仪(EDX)、紫外-可见漫反射光谱(UV-DRS)和比表面及孔隙度分析仪(ASAP)对该材料进行表征,合成的介孔TiO2BET比表面积为241 m2/g,平均孔直径为3.5nm。通过光催化降解甲基橙实验,发现介孔TiO2具有较高光催化活性。     

Polymorphic transformation of titanium dioxide by mechanical grinding

The effect of mechanical grinding on the structural transformation of titanium dioxide was studied by using several anatase samples prepared from different starting materials and with various particle sizes. Three anatase samples were prepared by hydrolysis of Ti(O·i-C₃H₇)₄, TiCl₄, and TiOSO₄·2H₂O and one is commercial reagent grade anatase. Each of the as-prepared or heat-treated samples (1.0 g) was ground in a mortar of sintered alumina for up to 96 h in air. The stability of brookite synthesized by grinding was examined by heating in air and under hydrothermal pressure. From the relative amount of the phases estimated by the measurement of the integrated intensity of X-ray line profile and of X-ray crystallite size, DTA and TG, IR spectra, and observation by electron microscope, it is concluded that: 1. the transformation proceeds by a consecutive process from anatase to rutile through brookite by grinding; 2. the smaller the initial particle size of anatase, the more stable the intermediate phase of brookite; 3. the very fine crystals of 520 nm of anatase can be grown to 50150 nm of rutile by grinding for 96 h; 4. the rate process of the transformation depends on the initial particle size and is independent of the difference in starting materials or of surface adsorbants; 5. an appropriate lattice distortion introduced by grinding is considered to stabilize the brookite phase; and 6. the lattice constant and the density of brookite synthesized by grinding,a ₀=0.5447±0.005 nm,b ₀=0.9150±0.0005 nm,c ₀=0.5141±0.0005 nm, andD _x =4.14 g cm^–3 agree with those in natural brookite.     

Synthesis of nanocrystalline titanium nitride by reacting titanium dioxide with sodium amide

A new method for synthesis of nanocrystalline titanium nitride was developed through the reaction of titanium oxide and sodium amide at 500–600 °C for 12 h in an autoclave. X-ray diffraction (XRD) and electron diffraction (SAED) results indicated the product had a cubic phase with lattice parameter a = 4.242 Å. Transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) revealed that the particle sizes were 10 to 40 nm. Quantitative analysis using X-ray photoelectron spectrum (XPS) showed the atomic ratio Ti:N was 1.03:1.     

Electrospun titanium dioxide nanofibers containing hydroxyapatite and silver nanoparticles as future implant materials

In this study, a good combination consisting of electrospun titanium dioxide (TiO₂) nanofibers incorporated with high purity hydroxyapatite (HAp) nanoparticles (NPs) and antimicrobial silver NPs is introduced for hard tissue engineering applications. The synthesized nanofibers were characterized by various state of art techniques like; SEM, XRD, TEM, TEM EDS and XPS analyses. SEM results confirmed well oriented nanofibers and good dispersion of HAp and silver NPs, respectively. XRD results demonstrated well crystalline feature of three components used for electrospinning. Silver NPs were having a diameter in range of 5–8 nm indicated by TEM analysis. Moreover, TEM EDS analysis demonstrated the presence of each component with good dispersion over TiO₂ nanofiber. The surface analyses of nanofibers were investigated by XPS which indicated the presence of silver NPs on the surfaces of nanofibers. The obtained nanofibers were checked for antimicrobial activity by using two model organisms E. coli and S. aureus. Subsequently, antimicrobial tests have indicated that the prepared nanofibers do posses high bactericidal effect. Accordingly, these results strongly recommend the use of obtained nanofiber mats as future implant materials.     

Electron transport in dye-sanitized solar cell with tin-doped titanium dioxide as photoanode materials

Journal of Materials Science: Materials in Electronics - Pure and tin-incorporated TiO2 (Sn-TiO2) nanoparticles were prepared utilizing photolysis method. Field emission-scanning electron...     

Nano-crystalline titanium dioxide formed by reactive plasma synthesis

Nano-crystalline titanium dioxide finds extensive applications in photocatalytic degradation of harmful organic compounds pollutants in air and water. Synthesis and characterization of nano-crystalline TiO₂ powder by reactive thermal plasma synthesis is presented here. Processing was carried out in a plasma reactor designed and developed in our laboratory. TiH₂ powder was used as the precursor, which was injected into the thermal plasma jet along with air as the reactive gas. TiH₂ particles, as they traverse the plasma jet, react with oxygen to form nano-sized TiO₂ powder. Nano-sized TiO₂ was also synthesized using Ti powder as the precursor. X-ray diffraction results showed complete conversion of the precursor into oxide. More than 75% of TiO₂ formed was present as anatase. TEM showed well-resolved nano-sized particles with more than 70% lying in the range of a few nanometer to 20 nm. The powder has been used to study photocatalytic degradation of dye.     

Drop-coated titanium dioxide memristors

The fabrication of memristors by drop-coating sol–gel Ti(OH)₄ solution onto either aluminium foil or sputter-coated aluminium on plastic is presented. The gel layer is thick, 37 μm, but both devices exhibit good memristance I–V profiles. The drop coated aluminium foil memristors compare favourably with the sputter-coated ones, demonstrating an expansion in the accessibility of memristor fabrication. A comparison between aluminium and gold for use as the sputter-coated electrodes shows that aluminium is the better choice as using gold leads to device failure. The devices do not require a forming step.     

Photocatalytic titanium dioxide composite

In recent years, Titanium Dioxide (TiO2) has gained much more interest for its semiconducting properties for use as photocatalytic material because it rapidly and completely mineralizes organic without harmful byproducts. Based on inspiration from biology, which uses organic structures to guide nucleation and growth of minerals, we demonstrate controlled synthesis of TiO2 using a hydrophilic synthetic polymer. In the absence of the polymer, TiO2 completely transforms to rutile by 72 hours, however with the addition of the polymer larger anatase crystallites are observed due to the reduced number of nuclei formed. Under these conditions, complete transformation to rutile was not observed due to diffusion-limited growth of TiO2 as well as the presence of an organic coating on the crystallites. However nanoparticles are difficult to recover from effluent streams. We use the polymer to develop bulk composite TiO2-organic structures which can be fabricated and tailored as a stand alone photocatalysts, eliminating the need for nanoparticle recovery systems, thereby reducing processing costs.     

Recent advances in titanium dioxide/graphene photocatalyst materials as potentials of energy generation

The properties of titanium dioxide (\(\hbox {TiO}_{2})\)/graphene/graphene oxides (GO) are examined in this study. These views summarize the recent theoretical and experimental novel approaches in the catalytic activity of \(\hbox {TiO}_{2}\)/graphene interface. Imperative results at a level of detail, suitable for upcoming experimental and theoretical researchers involved an overview of the enthralling characteristics of \(\hbox {TiO}_{2}\) and graphene composites were presented. Aspects like crystal lattice, electronic band structure and phonon dispersion, among others that were used to describe the properties of a \(\hbox {TiO}_{2}\) interface with pristine graphene and graphene dioxide among other composites are discussed. In particular, this review covers reactivity, binding energies, geometric structures as well as the photocatalytic activity of anatase \(\hbox {TiO}_{2}\) surfaces with graphene and graphene oxide with hybrid nanocomposites. These views also explore the understanding of the \(\hbox {TiO}_{2}\) interactions with graphene and possible applications. Finally, highlights on the challenges and proposed strategies in developing advanced photocatalytic semiconductor-based composites for water-splitting applications are provided.     

静电自组装制备纳米TiO2/膨润土复合材料及其光催化性能研究

选用具有优异吸附性的膨润土为载体,采用巯基硅烷偶联剂对膨润土进行干法改性,硅烷偶联剂巯基基团经氧化剂氧化为易电离的磺酸基后,静电自组装制备纳米TiO2/膨润土复合光催化材料.采用XRD对材料的成分和结构进行分析,ESEM对材料微观形貌进行分析,采用甲基橙染料废水评价材料的光催化脱色性能,研究表明:在光照初期,复合材料即...     

Synthesis of hexatitanate and titanium dioxide fibers by ion-exchange approach

Hexatitanate (K₂Ti₆O₁₃) and titanium dioxide (TiO₂) fibers were synthesized by ion-exchange method using fibrous potassium titanate (K₄Ti₃O₈) as initial material. Fibrous K₄Ti₃O₈ was prepared by treating TiO₂ with 80 wt.% concentrated KOH solution at 220 °C for 2 h under atmospheric pressure. Then, high qualities of K₂Ti₆O₁₃ and TiO₂ fibers were formed by a thermal treatment of the hydrolytic intermediates K_4−bH_bTi₃O₈ (1.2 ≤ b ≤ 3.0) and H₄Ti₃O₈, which were quantitatively obtained by controlling the pH value ranging from 10.9 to 12.0 and from 2.0 to 5.0 in the hydrolytic process of K₄Ti₃O₈, respectively. Based on the experimental results, the possible ion-exchange and phase transformation mechanisms in the reaction process were discussed.     

Synthesis of mesostructured titanium dioxide films by surfactant-templated sol-gel method

Mesostructured titanium dioxide films have been synthesized by modifying sol-gel methods in the presence of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) block copolymer surfactants as a structure-directing agent. The synthesized films were analyzed using X-ray diffraction (XRD), field emission transmission electron microscopy (FE-TEM) and selected area electron diffraction (SAED). XRD investigation revealed that as-deposited and as-dried films showed a hexagonal arrangement. With increasing heat-treatment temperature, the mesostructure of the films degraded. From TEM and SAED studies, the degradation of the mesostructure can be explained by the grain growth of microcrystalline titanium dioxide.     

Synthesis of titanium dioxide nanoparticles by reactive DC magnetron sputtering

Nanometer-sized titanium dioxide (TiO₂) particles were prepared on carbon substrates by reactive direct-current magnetron sputtering. By performing measurements with high resolution electron microscopes, the mean nanoparticle diameter and the coverage fraction of the substrate by the nanoparticles (NPs) were measured at 19 nm and 30%, respectively. Moreover, electron diffraction analysis showed that the TiO₂ NPs' crystalline structure on the carbon substrate was a mixture of anatase and rutile. Finally, we provided information on the TiO₂ initial growth stage: crystalline NPs were formed after deposition of amorphous nanoparticles on the substrate and heating.     

Reactive sputter deposition of titanium dioxide

The microstructural, optical and electrical properties of reactively sputtered TiO_x films have been examined at points along the reactive deposition hysteresis curve. The deposition process utilizes feedback control loops of the current and oxygen/argon flowrates for operation in the internal region of the hysteresis curve. The variations in the optical properties are well correlated to the process conditions and the microstructure. For thicknesses of 60–100 nm, the films are polycrystalline for low deposition/high oxygen flow rates, and become amorphous for high deposition/low oxygen flow rates. Electron diffraction ring patterns of the polycrystalline phase are best fit to the d-spacings of the rutile structure. The index of refraction at 550 nm for the rutile phase polycrystalline films (10 nm grain size) is 2.6, this falls to 2.4 as the films become amorphous, and rises to 2.5 as the films become oxygen substoichiometric. We find the variation of the optical band gap of TiO_x to be less than 1%, and is less indicative of chemical and/or microstructural changes than the extinction coefficient at higher energies in the visible. The index of extinction at 350 nm shows a minimum at the same point as the index of refraction at 550 nm. We find the indirect fit of Tauc to the index of extinction gives the most linear fit. Variations in the complex index of refraction are consistent with the processing of r.f. sputtered films from titania targets.